// SPDX-License-Identifier: GPL-2.0
/*
 * AD7606 SPI ADC driver
 *
 * Copyright 2011 Analog Devices Inc.
 */

#include <linux/bitmap.h>
#include <linux/err.h>
#include <linux/math.h>
#include <linux/module.h>
#include <linux/pwm.h>
#include <linux/spi/offload/consumer.h>
#include <linux/spi/offload/provider.h>
#include <linux/spi/spi.h>
#include <linux/types.h>
#include <linux/units.h>

#include <linux/iio/buffer-dmaengine.h>
#include <linux/iio/iio.h>

#include <dt-bindings/iio/adc/adi,ad7606.h>

#include "ad7606.h"

#define MAX_SPI_FREQ_HZ         23500000        /* VDRIVE above 4.75 V */

struct spi_bus_data {
        struct spi_offload *offload;
        struct spi_offload_trigger *offload_trigger;
        struct spi_transfer offload_xfer;
        struct spi_message offload_msg;
};

static u16 ad7616_spi_rd_wr_cmd(int addr, char is_write_op)
{
        /*
         * The address of register consist of one w/r bit
         * 6 bits of address followed by one reserved bit.
         */
        return ((addr & 0x7F) << 1) | ((is_write_op & 0x1) << 7);
}

static u16 ad7606b_spi_rd_wr_cmd(int addr, char is_write_op)
{
        /*
         * The address of register consists of one bit which
         * specifies a read command placed in bit 6, followed by
         * 6 bits of address.
         */
        return (addr & 0x3F) | (((~is_write_op) & 0x1) << 6);
}

static int ad7606_spi_read_block(struct device *dev,
                                 int count, void *buf)
{
        struct spi_device *spi = to_spi_device(dev);
        int i, ret;
        unsigned short *data = buf;
        __be16 *bdata = buf;

        ret = spi_read(spi, buf, count * 2);
        if (ret < 0) {
                dev_err(&spi->dev, "SPI read error\n");
                return ret;
        }

        for (i = 0; i < count; i++)
                data[i] = be16_to_cpu(bdata[i]);

        return 0;
}

static int ad7606_spi_read_block14to16(struct device *dev,
                                       int count, void *buf)
{
        struct spi_device *spi = to_spi_device(dev);
        struct spi_transfer xfer = {
                .bits_per_word = 14,
                .len = count * sizeof(u16),
                .rx_buf = buf,
        };

        return spi_sync_transfer(spi, &xfer, 1);
}

static int ad7606_spi_read_block18to32(struct device *dev,
                                       int count, void *buf)
{
        struct spi_device *spi = to_spi_device(dev);
        struct spi_transfer xfer = {
                .bits_per_word = 18,
                .len = count * sizeof(u32),
                .rx_buf = buf,
        };

        return spi_sync_transfer(spi, &xfer, 1);
}

static int ad7606_spi_reg_read(struct ad7606_state *st, unsigned int addr)
{
        struct spi_device *spi = to_spi_device(st->dev);
        struct spi_transfer t[] = {
                {
                        .tx_buf = &st->d16[0],
                        .len = 2,
                        .cs_change = 1,
                }, {
                        .rx_buf = &st->d16[1],
                        .len = 2,
                },
        };
        int ret;

        st->d16[0] = cpu_to_be16(st->bops->rd_wr_cmd(addr, 0) << 8);

        ret = spi_sync_transfer(spi, t, ARRAY_SIZE(t));
        if (ret < 0)
                return ret;

        return be16_to_cpu(st->d16[1]);
}

static int ad7606_spi_reg_write(struct ad7606_state *st,
                                unsigned int addr,
                                unsigned int val)
{
        struct spi_device *spi = to_spi_device(st->dev);

        st->d16[0] = cpu_to_be16((st->bops->rd_wr_cmd(addr, 1) << 8) |
                                  (val & 0xFF));

        return spi_write(spi, &st->d16[0], sizeof(st->d16[0]));
}

static int ad7606b_sw_mode_config(struct iio_dev *indio_dev)
{
        struct ad7606_state *st = iio_priv(indio_dev);

        /* Configure device spi to output on a single channel */
        return st->bops->reg_write(st, AD7606_CONFIGURATION_REGISTER,
                                   AD7606_SINGLE_DOUT);
}

static const struct spi_offload_config ad7606_spi_offload_config = {
        .capability_flags = SPI_OFFLOAD_CAP_TRIGGER |
                            SPI_OFFLOAD_CAP_RX_STREAM_DMA,
};

static int ad7606_spi_offload_buffer_postenable(struct iio_dev *indio_dev)
{
        const struct iio_scan_type *scan_type;
        struct ad7606_state *st = iio_priv(indio_dev);
        struct spi_bus_data *bus_data = st->bus_data;
        struct spi_transfer *xfer = &bus_data->offload_xfer;
        struct spi_device *spi = to_spi_device(st->dev);
        struct spi_offload_trigger_config config = {
                .type = SPI_OFFLOAD_TRIGGER_DATA_READY,
        };
        int ret;

        scan_type = &indio_dev->channels[0].scan_type;

        xfer->bits_per_word = scan_type->realbits;
        xfer->offload_flags = SPI_OFFLOAD_XFER_RX_STREAM;
        /*
         * Using SPI offload, storagebits are related to the spi-engine
         * hw implementation, can be 16 or 32, so can't be used to compute
         * struct spi_transfer.len. Using realbits instead.
         */
        xfer->len = (scan_type->realbits > 16 ? 4 : 2) *
                    st->chip_info->num_adc_channels;

        spi_message_init_with_transfers(&bus_data->offload_msg, xfer, 1);
        bus_data->offload_msg.offload = bus_data->offload;

        ret = spi_optimize_message(spi, &bus_data->offload_msg);
        if (ret) {
                dev_err(st->dev, "failed to prepare offload, err: %d\n", ret);
                return ret;
        }

        ret = spi_offload_trigger_enable(bus_data->offload,
                                         bus_data->offload_trigger,
                                         &config);
        if (ret)
                goto err_unoptimize_message;

        ret = ad7606_pwm_set_swing(st);
        if (ret)
                goto err_offload_exit_conversion_mode;

        return 0;

err_offload_exit_conversion_mode:
        spi_offload_trigger_disable(bus_data->offload,
                                    bus_data->offload_trigger);

err_unoptimize_message:
        spi_unoptimize_message(&bus_data->offload_msg);

        return ret;
}

static int ad7606_spi_offload_buffer_predisable(struct iio_dev *indio_dev)
{
        struct ad7606_state *st = iio_priv(indio_dev);
        struct spi_bus_data *bus_data = st->bus_data;
        int ret;

        ret = ad7606_pwm_set_low(st);
        if (ret)
                return ret;

        spi_offload_trigger_disable(bus_data->offload,
                                    bus_data->offload_trigger);
        spi_unoptimize_message(&bus_data->offload_msg);

        return 0;
}

static const struct iio_buffer_setup_ops ad7606_offload_buffer_setup_ops = {
        .postenable = ad7606_spi_offload_buffer_postenable,
        .predisable = ad7606_spi_offload_buffer_predisable,
};

static bool ad7606_spi_offload_trigger_match(
                                struct spi_offload_trigger *trigger,
                                enum spi_offload_trigger_type type,
                                u64 *args, u32 nargs)
{
        if (type != SPI_OFFLOAD_TRIGGER_DATA_READY)
               return false;

        /*
         * Requires 1 arg:
         * args[0] is the trigger event.
         */
        if (nargs != 1 || args[0] != AD7606_TRIGGER_EVENT_BUSY)
                return false;

        return true;
}

static int ad7606_spi_offload_trigger_request(
                                struct spi_offload_trigger *trigger,
                                enum spi_offload_trigger_type type,
                                u64 *args, u32 nargs)
{
        /* Should already be validated by match, but just in case. */
        if (nargs != 1)
                return -EINVAL;

        return 0;
}

static int ad7606_spi_offload_trigger_validate(
                                struct spi_offload_trigger *trigger,
                                struct spi_offload_trigger_config *config)
{
        if (config->type != SPI_OFFLOAD_TRIGGER_DATA_READY)
                return -EINVAL;

        return 0;
}

static const struct spi_offload_trigger_ops ad7606_offload_trigger_ops = {
        .match = ad7606_spi_offload_trigger_match,
        .request = ad7606_spi_offload_trigger_request,
        .validate = ad7606_spi_offload_trigger_validate,
};

static int ad7606_spi_offload_probe(struct device *dev,
                                    struct iio_dev *indio_dev)
{
        struct ad7606_state *st = iio_priv(indio_dev);
        struct spi_device *spi = to_spi_device(dev);
        struct spi_bus_data *bus_data;
        struct dma_chan *rx_dma;
        struct spi_offload_trigger_info trigger_info = {
                .fwnode = dev_fwnode(dev),
                .ops = &ad7606_offload_trigger_ops,
                .priv = st,
        };
        int ret;

        bus_data = devm_kzalloc(dev, sizeof(*bus_data), GFP_KERNEL);
        if (!bus_data)
                return -ENOMEM;
        st->bus_data = bus_data;

        bus_data->offload = devm_spi_offload_get(dev, spi,
                                                 &ad7606_spi_offload_config);
        ret = PTR_ERR_OR_ZERO(bus_data->offload);
        if (ret && ret != -ENODEV)
                return dev_err_probe(dev, ret, "failed to get SPI offload\n");
        /* Allow main ad7606_probe function to continue. */
        if (ret == -ENODEV)
                return 0;

        ret = devm_spi_offload_trigger_register(dev, &trigger_info);
        if (ret)
                return dev_err_probe(dev, ret,
                                     "failed to register offload trigger\n");

        bus_data->offload_trigger = devm_spi_offload_trigger_get(dev,
                bus_data->offload, SPI_OFFLOAD_TRIGGER_DATA_READY);
        if (IS_ERR(bus_data->offload_trigger))
                return dev_err_probe(dev, PTR_ERR(bus_data->offload_trigger),
                                     "failed to get offload trigger\n");

        /* TODO: PWM setup should be ok, done for the backend. PWM mutex ? */
        rx_dma = devm_spi_offload_rx_stream_request_dma_chan(dev,
                                                             bus_data->offload);
        if (IS_ERR(rx_dma))
                return dev_err_probe(dev, PTR_ERR(rx_dma),
                                     "failed to get offload RX DMA\n");

        ret = devm_iio_dmaengine_buffer_setup_with_handle(dev, indio_dev,
                rx_dma, IIO_BUFFER_DIRECTION_IN);
        if (ret)
                return dev_err_probe(dev, ret,
                                     "failed to setup offload RX DMA\n");

        /* Use offload ops. */
        indio_dev->setup_ops = &ad7606_offload_buffer_setup_ops;

        st->offload_en = true;

        return 0;
}

static int ad7606_spi_update_scan_mode(struct iio_dev *indio_dev,
                                       const unsigned long *scan_mask)
{
        struct ad7606_state *st = iio_priv(indio_dev);

        if (st->offload_en) {
                unsigned int num_adc_ch = st->chip_info->num_adc_channels;

                /*
                 * SPI offload requires that all channels are enabled since
                 * there isn't a way to selectively disable channels that get
                 * read (this is simultaneous sampling ADC) and the DMA buffer
                 * has no way of demuxing the data to filter out unwanted
                 * channels.
                 */
                if (!bitmap_full(scan_mask, num_adc_ch))
                        return -EINVAL;
        }

        return 0;
}

static const struct ad7606_bus_ops ad7606_spi_bops = {
        .offload_config = ad7606_spi_offload_probe,
        .read_block = ad7606_spi_read_block,
        .update_scan_mode = ad7606_spi_update_scan_mode,
};

static const struct ad7606_bus_ops ad7607_spi_bops = {
        .offload_config = ad7606_spi_offload_probe,
        .read_block = ad7606_spi_read_block14to16,
        .update_scan_mode = ad7606_spi_update_scan_mode,
};

static const struct ad7606_bus_ops ad7608_spi_bops = {
        .offload_config = ad7606_spi_offload_probe,
        .read_block = ad7606_spi_read_block18to32,
        .update_scan_mode = ad7606_spi_update_scan_mode,
};

static const struct ad7606_bus_ops ad7616_spi_bops = {
        .offload_config = ad7606_spi_offload_probe,
        .read_block = ad7606_spi_read_block,
        .reg_read = ad7606_spi_reg_read,
        .reg_write = ad7606_spi_reg_write,
        .rd_wr_cmd = ad7616_spi_rd_wr_cmd,
        .update_scan_mode = ad7606_spi_update_scan_mode,
};

static const struct ad7606_bus_ops ad7606b_spi_bops = {
        .offload_config = ad7606_spi_offload_probe,
        .read_block = ad7606_spi_read_block,
        .reg_read = ad7606_spi_reg_read,
        .reg_write = ad7606_spi_reg_write,
        .rd_wr_cmd = ad7606b_spi_rd_wr_cmd,
        .sw_mode_config = ad7606b_sw_mode_config,
        .update_scan_mode = ad7606_spi_update_scan_mode,
};

static const struct ad7606_bus_ops ad7606c_18_spi_bops = {
        .offload_config = ad7606_spi_offload_probe,
        .read_block = ad7606_spi_read_block18to32,
        .reg_read = ad7606_spi_reg_read,
        .reg_write = ad7606_spi_reg_write,
        .rd_wr_cmd = ad7606b_spi_rd_wr_cmd,
        .sw_mode_config = ad7606b_sw_mode_config,
        .update_scan_mode = ad7606_spi_update_scan_mode,
};

static const struct ad7606_bus_info ad7605_4_bus_info = {
        .chip_info = &ad7605_4_info,
        .bops = &ad7606_spi_bops,
};

static const struct ad7606_bus_info ad7606_8_bus_info = {
        .chip_info = &ad7606_8_info,
        .bops = &ad7606_spi_bops,
};

static const struct ad7606_bus_info ad7606_6_bus_info = {
        .chip_info = &ad7606_6_info,
        .bops = &ad7606_spi_bops,
};

static const struct ad7606_bus_info ad7606_4_bus_info = {
        .chip_info = &ad7606_4_info,
        .bops = &ad7606_spi_bops,
};

static const struct ad7606_bus_info ad7606b_bus_info = {
        .chip_info = &ad7606b_info,
        .bops = &ad7606b_spi_bops,
};

static const struct ad7606_bus_info ad7606c_16_bus_info = {
        .chip_info = &ad7606c_16_info,
        .bops = &ad7606b_spi_bops,
};

static const struct ad7606_bus_info ad7606c_18_bus_info = {
        .chip_info = &ad7606c_18_info,
        .bops = &ad7606c_18_spi_bops,
};

static const struct ad7606_bus_info ad7607_bus_info = {
        .chip_info = &ad7607_info,
        .bops = &ad7607_spi_bops,
};

static const struct ad7606_bus_info ad7608_bus_info = {
        .chip_info = &ad7608_info,
        .bops = &ad7608_spi_bops,
};

static const struct ad7606_bus_info ad7609_bus_info = {
        .chip_info = &ad7609_info,
        .bops = &ad7608_spi_bops,
};

static const struct ad7606_bus_info ad7616_bus_info = {
        .chip_info = &ad7616_info,
        .bops = &ad7616_spi_bops,
};

static int ad7606_spi_probe(struct spi_device *spi)
{
        const struct ad7606_bus_info *bus_info = spi_get_device_match_data(spi);

        return ad7606_probe(&spi->dev, spi->irq, NULL,
                            bus_info->chip_info, bus_info->bops);
}

static const struct spi_device_id ad7606_id_table[] = {
        { "ad7605-4", (kernel_ulong_t)&ad7605_4_bus_info },
        { "ad7606-4", (kernel_ulong_t)&ad7606_4_bus_info },
        { "ad7606-6", (kernel_ulong_t)&ad7606_6_bus_info },
        { "ad7606-8", (kernel_ulong_t)&ad7606_8_bus_info },
        { "ad7606b",  (kernel_ulong_t)&ad7606b_bus_info },
        { "ad7606c-16", (kernel_ulong_t)&ad7606c_16_bus_info },
        { "ad7606c-18", (kernel_ulong_t)&ad7606c_18_bus_info },
        { "ad7607",   (kernel_ulong_t)&ad7607_bus_info },
        { "ad7608",   (kernel_ulong_t)&ad7608_bus_info },
        { "ad7609",   (kernel_ulong_t)&ad7609_bus_info },
        { "ad7616",   (kernel_ulong_t)&ad7616_bus_info },
        { }
};
MODULE_DEVICE_TABLE(spi, ad7606_id_table);

static const struct of_device_id ad7606_of_match[] = {
        { .compatible = "adi,ad7605-4", .data = &ad7605_4_bus_info },
        { .compatible = "adi,ad7606-4", .data = &ad7606_4_bus_info },
        { .compatible = "adi,ad7606-6", .data = &ad7606_6_bus_info },
        { .compatible = "adi,ad7606-8", .data = &ad7606_8_bus_info },
        { .compatible = "adi,ad7606b", .data = &ad7606b_bus_info },
        { .compatible = "adi,ad7606c-16", .data = &ad7606c_16_bus_info },
        { .compatible = "adi,ad7606c-18", .data = &ad7606c_18_bus_info },
        { .compatible = "adi,ad7607", .data = &ad7607_bus_info },
        { .compatible = "adi,ad7608", .data = &ad7608_bus_info },
        { .compatible = "adi,ad7609", .data = &ad7609_bus_info },
        { .compatible = "adi,ad7616", .data = &ad7616_bus_info },
        { }
};
MODULE_DEVICE_TABLE(of, ad7606_of_match);

static struct spi_driver ad7606_driver = {
        .driver = {
                .name = "ad7606",
                .of_match_table = ad7606_of_match,
                .pm = AD7606_PM_OPS,
        },
        .probe = ad7606_spi_probe,
        .id_table = ad7606_id_table,
};
module_spi_driver(ad7606_driver);

MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD7606 ADC");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS("IIO_AD7606");
MODULE_IMPORT_NS("IIO_DMAENGINE_BUFFER");